TITANIUM RESEARCH & DEVELOPMENT FOR NAVAL

APPLICATIONS

Ernie Czyryca & Mike WellsNaval Surface Warfare CenterCarderock DivisionWest Bethesda, Maryland

TITANIUM 200622nd ITA Conference & Exposition

01 – 04 October 2006, San Diego CA

Requirements for Navy Materials

Higher StrengthWeight ReductionIncreased PerformanceIncreased Payload

Improved WeldabilityStructural FabricationRepair Welding

SurvivabilityShock / Blast LoadingToughness @ Low TemperaturesBallistic Resistance

AffordabilityAcquisition CostLife Cycle Cost

Surface Combatant – DDG 1000

Navy Littoral Operations

Marine Corps EFV

Reduced Surface Ship Signatures Required - RF, IR, Visible, Magnetic, Acoustic

Hardness Against Underwater Explosions (UNDEX), Air Blast,

Ballistic and Fragment Penetration

Reduced Submarine and UUV Magnetic and Acoustic

Signatures

Increased Speed & Improved Protection Systems

Titanium for Marine Service

• Titanium offers excellent strength-to-weight benefit

• Range of strengths available through alloy selection (50 to 115 ksi yield strength)

• No seawater corrosion concerns• Less maintenance man-hours required• High recycle value or re-use possible• Excellent fire and shock resistance• No ductile-to-brittle toughness transition• Nonmagnetic• Excellent compatibility with composites

TITANIUM & Ti ALLOY USAGE IN USN SHIPS

136,650LPD 1731,375SSN 77475,175SSN 2131,375SSBN / SSGN31,375SSN 68833,700DDG 5120,800CG 4716,500CVN 68

Total Weight of Titaniumper Ship (lb)Ship Class

• Metallic Material Advanced Development & Certification Program– Project on Ti 5111 Evaluation for Critical Applications– Certification of Ti-5111 Fasteners for Shock Applications

• Unmanned Undersea Vehicle (UUV) Pressure Hulls– Investment Cast Ti-5111 & Ti CP-2LO– Ti-5111 Forgings

• Titanium Welding Fabrication R&D Projects– FSW, Flux-assisted Welding (Including FCAW), GMAW-PA– Laser Peening for Weld Fatigue Improvement

• CVN 21 Manufacturing Technology Project– Titanium Applications– Ballistic Testing

• Technical Support to Low-Cost Ti Program (DARPA)– Evaluation of Solid-State Ti Plate (Armstrong Process)– Ti Applications – Future Navy / Navy After Next

• ALVIN HOV Technical Support– New Pressure Hull (Ti-6Al-4V ELI Forgings)

Navy Titanium R&D Projects

Ti-5111 = Ti 5Al-1V-1Sn-1Zr-.8Mo-.1Si• Developed under ONR/TIMET project as a tough,

weldable, high strength alloy• More producible alternate to Navy Ti-100 (Ti-6211)• Commercially available since late 1990’s• Corrosion resistance equal to CP grade 2 or Ti-6-4

ELI titanium• No SCC concerns in sea water• Displays highest toughness of any high strength Ti

alloy• Product forms are plate, sheet, bar, rod, castings,

forgings, & fasteners• Continuing focus of Navy projects to certify Ti-5111

for critical ship and submarine applications

Ti - 5111 Marine Grade Aloy

Ti-5111 Evaluation

OBJECTIVE: Support approval and certification for critical applications in surface ships and submarines

• Mechanical & physical properties of Ti-5111 plate, bar, forgings, castings and weldments (weld metal & HAZ)

• Ti-5111 products under evaluation:– ¼, ½, 1, and 2 inch thick plate– GTAW weld metal & HAZ in 1-inch plate– ½, 1, 2, 3½, and 4 inch diameter bar– 8-inch diameter forging– Graphite mold & Investment cast plates

• Evaluation of Ti-5111 fasteners for wetted, shock applications

• Draft NAVSEA Technical Publication, “Requirements for Titanium & Titanium Alloys for Ship and Submarine Applications”

Ti-5111 Evaluation

• Procure Ti-5111 Products• Tensile Properties• Charpy V-notch Properties• Dynamic Tear Properties• Fracture Toughness• Hardness• Compression Properties• Thermal Properties• Elastic Constants

• Dynamic Tensile Properties• Dynamic Fracture Toughness• Low-Cycle Fatigue Properties• High-Cycle Fatigue Properties• Fatigue Crack Growth Rates• Corrosion Fatigue Properties• Structural Element Tests• Explosion Tests• Stress Corrosion Properties

Ti-5111 Engineering Data Developed

Ti-5111 Fatigue Properties

y = 0.131x-0.25

0.001

0.010

0.100

10 100 1000 10000 100000 1000000 10000000

Cycles to failure

Tota

l str

ain

rang

e

TransverseLongitudinal

10

20

30

40

50

60

70

80

90

100

1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08 1.E+09

Cycles to Failure

Stre

ss A

mpl

itude

(ksi

)

Smooth/AirSmooth/SWNotched/AirNotched/SW

10

100

1000

10 100 1000 10000 100000 1000000 10000000 100000000 1E+09Cycles

Stre

ss (k

si)

Experimental dataPeterson correctionFatigue Design Curve

Low-Cycle Fatigue

High-Cycle Fatigue

Design Fatigue Curve

Displacement (in)

0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035

Load

(lbs

)

0

10000

20000

30000

40000

50000Ti-5111 Fastener Structural Element Test1.125-in (29 mm) Diameter BarHIB-14 3/4"-10

Load vs. DisplacementTi-5111Fastener Test

EDM Flaw

Fastener Dynamic Fracture Test

Test stopped prior to failure

Ti-5111 Navy Service ApplicationExtensive evaluation for Submarine Communications Mast StructureMast is welded Ti-5111 structure – plate, bar, & forgingOver 45 Masts deployed / first deployed in 2000

Ti-5111 for Naval Applications

Cast Titanium & Ti-5111 Alloy

Trial CastingTi-5111 UUV Hull Section

Trial CastingTi CP-2LO UUV Hull

Section

High-Speed Ships(LCS)

Castings (Waterjet components -impellers, pump casings, ducts)

Unmanned Undersea Vehicles (UUV)

Near net-shape pressure hull castings

Hull Inserts, Penetrations

Cast Ti Fracture Toughness0.15-in Thick Ti-5111 Investment Casting

Cast Ti-5111 1-in Thick

Cast Ti CP-2 1-in Thick

Titanium WeldingCost Drivers

• Specialized gas shielding• Low productivity welding

processes• Labor intensive joint

designs and preparation procedures

High fabrication costs relative to steel and aluminum alloys limit Navy applications

ONR R&D GoalWeld large structures in a

shipyard environment⇒ Develop higher

productivity welding processes

– Flux-assisted & flux-cored arc welding

– Friction stir welding– Pulsed gas metal arc welding

with waveform control

Titanium Welding

Titanium Welding Fluxes– CaF2 based– Reagent grade purity

14--14BaCl2

15----MgF2

--28--SrF2

--20--LaF3

--7--BaF2

1--1NaF

704585CaF2

FormulaC

FormulaP-B

FormulaP-A

Chemical Composition, wt %

Titanium FCAW Feasibility

Ti FCAW Wire Drawing Demo– 0.160-inch OD to 0.055-inch OD, 22

dies at 5 mil reduction each– No intermediate annealing– Demonstrated reduction to 0.052-

inch OD– Wire breakage, 30-40m lengths

GTAW with Ti CP-2 flux-cored wire

Titanium Friction Stir Welding

Navy effort at EWI to develop friction stir welding of up to ½-

inch thick Ti-5111Work in progress to develop

tooling & process parameters

FSW Benefits• Fewer passes• Minimal joint preparation • Environmentally-friendly and

safe (no fume, arc, or spatter)• Solid state – minimal

distortion• Minimal post weld clean up• Reduced post weld inspection

(no porosity or lack of fusion)

Army project at EWI demonstrated FSW butt and

tee joints in ½-inch Ti-6Al-4V & model structures fabricated

Ti-5111 FSW

Titanium GMAW-PA

Ti-CP Weldment Produced with Double Pulse/Droplet WaveformDouble Pulse Waveform Definitions

for Wave Designer 2000

ONR Project - pulsed gas metal-arc welding process for all position welding of large structures

• Upgraded software and installed waveform algorithms• Fabricated weldments in Ti-CP grade 2 plate• Evaluation of mechanical properties in progress

Laser Peening of Ti-5111 Welds

• Produces high level of compressive residual stress

• Applied to 1-in thick weldment made with Ti-5111 filler wire by GTAW

• Machined 4 point bend fatigue coupons

• Peening at MIC and fatigue testing at UC-Davis in progress

• Extension of conventional shot peening• High intensity laser induces deep residual compressive stress• Residual stresses are influenced by processing parameters

• CVN 21 (CVN 78 & 79)Island StructureDoorsFastenersElevator PlatformsSponsonsPiping & ValvesArmor

CVN 21 - Potential Ti Applications

Challenges for Ti alloyTechnology Development

Processing & Alloy Development• Extraction Methods• Plasma Arc/EB Single Melting • Improved Ingot Casting ProcessesJoining Process Development• Flux-Assisted & Flux-Cored Arc Welding• Friction Stir Welding• High Productivity GMAW• Dissimilar Metal JoiningImproved Fatigue Performance• Weldment/Joint Design• Post Weld Treatments/Process

» Laser peening » Ultrasonic impact treatment» Low plasticity burnishing» Friction stir processing

SUMMARY

• Titanium is the optimum engineering material for seawater service

• Titanium has been successfully used in the Navy for decades, primarily in ship & submarine machinery systems

• Increased used and large structural applications are limited by high material & fabrication costs

• Although initial cost may be more than offset by reduced maintenance and end of life value, ship acquisition cost rules

• New opportunities exist for titanium to enhance structural efficiency of Navy ships for increased payload, range, stability, and operating cycles

• Development of lower cost Ti products and high productivity welding processes will be required to support increased usage

NSWC CarderockHM&E Technology for the Fleet

NSWC CarderockHM&E Technology for the Fleet

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